Facebook has a habit of turning low-profile CEOs into overnight celebrities. First it was Kevin Systrom, the Instagram head who was instantly the talk of the tech world when Facebook offered $1 billion for his 13-employee startup in April 2012. Today it’s Jan Koum, who just sold his mobile messaging platform WhatsApp to Facebook for $19 billion in cash and stock. Koum had been a relatively low-key CEO, giving few media interviews as his messaging service quietly grew even faster than Facebook had. But now that he’s at the center of the largest acquisition ever for a venture-backed startup, he’ll no doubt become a figure in the public sphere. Here’s what you need to know about Jan Koum:

His Origin Story: According to a profile by Forbes, Koum, 38, was born and raised near Kiev, Ukraine during the Soviet era. He lived as an only child in a house that didn’t have hot water. He moved to Mountain View, California as a teenager with his mother, and lived off food stamps for a time. He taught himself computer programming and earned a job as an infrastructure engineer at Yahoo in the late 1990s. After working at Yahoo for several years he decided to launch a messaging app through which people could send text messages via the Internet instead of through cellular SMS texting. Brian Acton, a friend of Koum’s at Yahoo, rallied the first seed funding for the new company was named a co-founder.

His Worldview: Koum’s upbringing in Ukraine gave him an appreciation for tight friend groups rather than the sprawling social networks that Americans often develop. He also gained an aversion for advertising there, and has consistently railed against its use as the monetization engine of the Web. According to a Wired profile, he has a sign in his office from his co-founder that reads “No ads! No games! No gimmicks!” In a 2012 WhatsApp blog post, he wrote a manifesto against the use of ads online, saying, “We wanted to make something that wasn’t just another ad clearinghouse…Remember, when advertising is involved you the user are the product.” After the Facebook acquisition, he held strong on his stance, saying that there are no plans to introduce ads to WhatsApp.

His Relationship With Mark Zuckerberg: Facebook’s CEO has been eyeing WhatsApp for a long time and first began courting Koum early in 2012. The two had a series of discussions in the ensuing years, over dinners and walks and hikes. Zuckerberg officially popped the question on Feb. 9, telling Koum, “If we joined together, that would help us really connect the rest of the world.” Koum considered for a few days, then visited Zuckerberg’s home on Valentine’s Day to accept the deal. The two reportedly hashed out the terms of the buyout over chocolate-covered strawberries.

His Plans for WhatsApp: In a conference call with analysts, Koum wouldn’t disclose any planned features for WhatsApp. He only offered that the company hopes to make messaging faster and more stable this year. But he did emphasize that, for now, the company is focusing on growth instead of monetization. With Zuckerberg himself saying that advertising isn’t appropriate for messaging services, WhatsApp will likely continue is $0.99-per-year subscription fee as its main revenue source. But given massive amount of money Facebook just doled out, the app’s new parent company no doubt has greater long-term aspirations for it as a revenue generator.

His Net Worth: Forbes estimates that Koum owns about 45 percent of WhatsApp, which would net him $6.8 billion in the deal. That figure dwarfs the amount the founders of Twitter received during the company’s IPO in November.

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